Coronary flow dynamics in the right coronary artery providing collateral circulation: Comparison before and after successful angioplasty with a Doppler catheter

Coronary blood flow dynamics were investigated in 9 patients with isolated coronary artery disease of the left anterior descending artery (LAD) with good collateral flow (grade 2 or 3 of Rentrop's classification) from the right coronary artery (RCA) and 20 patients with normal coronary arteries as controls. The coronary flow velocity (Vs: systolic peak, Vd: diastolic peak, Vm: mean) was measured with a Doppler catheter and the diameter (D) by the edge detection method in the proximal portion of the RCA. Vs/Vd was calculated. The areas under the velocity curve during systole (∫s) and diastole (∫d) were measured to obtain the ratio (∫s/∫d). Peak to resting velocity ratio (PRVR) was obtained as an index of coronary flow reserve, using intracoronary injections of 6 ml contrast medium or 8-12 mg papaverine. These parameters before percutaneous transluminal coronary angioplasty (PTCA), after PTCA, and in control subjects were compared. The collaterals disappeared angiographically immediately after successful PTCA. D (before PTCA: 3.2 ± 0.1 mm, after PTCA: 3.3 ± 0.1 mm, controls: 3.2 ± 0.1 mm) and Vs did not vary between before and after PTCA and in control subjects (NS). The values of Vd, Vm decreased and Vs/Vd and ∫s/∫d increased after PTCA to the values in the controls. PRVR obtained with contrast medium and papaverine also increased. PTCA caused the disappearance of the collaterals from the RCA to the LAD, decreased coronary flow, and restoration of coronary flow reserve in the right coronary artery.